Multi-unit structures such as apartment buildings and office buildings require systems for supplying hot and/or cold fluids. For example, apartment buildings generally require a system for supplying hot water that will be drawn off at sinks, bathtubs, and showers of the building. Hot or cold fluids such as water or air can be used to heat or cool a building. Many older buildings have simple fluid temperature controls. For example, a hot water supply system may supply hot water at the hot water tank outlet, at a constant temperature of 160.degree. F., which assures that even in times of maximum use (e.g. if many tenants are taking showers or baths on Saturday evening) there will be enough hot water for all tenants. In another example, a hot water heating system may supply hot water to the radiators at a constant temperature of 190.degree. F. except during summer months when the system is shut down. In such a heating system, tenants may be able to operate a manual valve to control the amount of hot water supply to their radiators, and may open the windows to limit room temperature.
It is well recognized that there is large heat losses in such simple prior systems, which can be minimized by installing a new control that varies the temperature of fluid to minimize heat losses. For example, the temperature of hot water in the supply tank may be reduced during early morning hours when there is very little demand. As another example, the temperature of hot water supplied in a room heating system may be varied according to the outdoor temperature. U.S. Pat. No. 4,832,259 by Vandermeyden (the inventor in the present application), describes a sophisticated hot water heater controller which varies hot water temperature in accordance with many factors including expected demand at a particular time of day, outdoor temperature, etc.
Applicant has found that when a new control is installed to replace a prior control, that the building manager will often receive many complaints from tenants. For example, a prior control for a hot water heating system may have always supplied hot water at 190.degree. F., although tenants can lower room temperature by partially closing water flow valves and opening windows. If the new system supplies water at a lower temperature such as 140.degree. F. at night under the same circumstances, then the tenant may complain that the radiator is too cold. Apparatus which minimize discomfort of tenants during a period after a new fluid temperature control was installed, until tenants became accustomed to the manner of operation of the new control, would minimized disruption of tenants and consequent problems of building managers, as well as encouraging the installation of new controls to minimize energy expenditures.